Traditionally, after multiple individual dies have been manufactured onto a single semiconductor wafer, the individual die are separated from the wafer by either cutting the wafer with a die saw or else using a nano-scrubbing process. In die sawing a large saw is used to cut the area of the wafer between adjacent dies, essentially cutting the individual die from the wafer. Unfortunately, die sawing, in addition to possible delamination and destruction of the die, also generates particles as the saw cuts through the wafer. These particles can then redeposit and contaminate the individual die, potentially causing bonding failures if the particles are larger than the bonding gap requirements (which may in some cases be less than 1 μm).
A nano-scrubbing process has been developed to singulate the wafer without using a die saw. In this process scrub lines are etched into one side of the wafer between the individual dies and to a depth consistent with the final dimension of the die. A carrier is attached to the wafer over the scrub lines, and the other side of the wafer (opposite the scrub lines) is thinned by grinding until the scrub lines are exposed, thereby singulating the wafer into individual die.
However, nano-scrubbing does not solve the problem of particles. Rather, particles may still be left within the scrub lines after the grinding process. These particles may remain after singulation and may still interfere with subsequent bonding of the die to other devices, thereby driving down the overall yield of wafers.
Accordingly, what is needed is a process of singulating individual die from a semiconductor wafer that prevents the deposition of these particles from occurring to increase the bond yield during subsequent bonding of the die.